ABSTRACT
This paper reports the residual status of forbidden and restricted pesticides of organophosphorus in Loincerae Japonicae Flos to provide reference for the risk control and the formulation of maximum residue limits of the flower. A method for the determination of residues of 23 forbidden and restricted pesticides of organophosphorus was established, and 64 collected samples were tested. Then a risk assessment based on the maximum residue limit was carried out. Results showed that the detection rate of samples was 58%. 6 of 23 pesticides were detected and the ratio was chlorpyrifos 41%, omethoate 23%, triazophos 11%, isofenphos-methyl 6.3%, methamidophos 1.6%, isocarbophos 1.6%, respectively. And the median of pesticide residues in the positive samples was chlorpyrifos 0.037 mg·kg⁻¹, omethoate 0.043 mg·kg⁻¹, triazophos 0.030 mg·kg⁻¹, isofenphos-methyl 0.18 mg·kg⁻¹, methamidophos 0.041 mg·kg⁻¹, isocarbophos 0.041 mg·kg⁻¹, respectively. In the samples with pesticide residues, the residue amount of methamidophos and isocarbophos was lower than the theoretical maximum residue limit, and the residue amount of chlorpyrifos, isofenphos-methyl, triazophos were higher than it individually, while, all the residue amount of omethoate was higher than it. According to the assessment result of theoretical maximum residue limit, it is suggested that relevant departments should accelerate the formulation of the maximum residue limit standard, and strengthen the supervision of the use of forbidden and restricted pesticides of organophosphorus in Loincerae Japonicae Flos.
ABSTRACT
This paper reports the residual dynamics of deltamethrin and detection method in Loincerae Japonicae Flos to provide scientific basis for safe and appropriate use of deltamethrin. A field experiment was conducted in Fengqiu, Henan Province China. The field plots were sprayed with deltamethrin at the recommended dose and a high dose, respectively, and a control was set up, totally being 3 treatments with 3 replications. The flowers were picked at 2 hours, 1, 2, 3, 4, 5, 7, 9, 11, 13 and 15 days after pesticide application and then dried. The residue of deltamethrin was determined by gas chromatography method with electron capture detector for the above samples. Results showed that recoveries of deltamethrin ranged from 76.4% to 86.9%,and the relative standard deviation was below 11%,Linearity was observed over a range of 5-500 μg•L ⁻¹ with correlation coefficient was 0. 999 2. The established method meets the requirements of pesticide residue analytical methods. The degradation of deltamethrin followed the first order dynamics. The residue dynamic equation of the high dose and recommended dose deltamethrin were C=5.992 2e-0.338t and C=1.536 9e-0.31t respectively, and the half-life of deltamethrin in Loincerae Japonicae Flos was 2.09-2.24 days, which indicates that deltamethrin is an easily degradable pesticide. It is concluded that deltamethrin should be used in aphids occurring period and the safety interval was more than 7 days to ensure the safety of Loincerae Japonicae Flos consuming.